Parca crashes if the agent sends a stackframes write with empty filenames.

[umanwizard]

To repro: apply this diff to latest main of parca-agent:

diff --git a/reporter/parca_reporter.go b/reporter/parca_reporter.go
index 52d1cd2c..d2535e74 100644
--- a/reporter/parca_reporter.go
+++ b/reporter/parca_reporter.go
@@ -804,7 +804,8 @@ func (r *ParcaReporter) buildStacktraceRecord(ctx context.Context, stacktraceIDs
 				w.LineNumber.Append(int64(0))
 				w.FunctionName.AppendString(symbol)
 				w.FunctionSystemName.AppendString("")
-				w.FunctionFilename.AppendString("vmlinux")
+				// w.FunctionFilename.AppendString("vmlinux")
+				w.FunctionFilename.AppendString("")
 				w.FunctionStartLine.Append(int64(0))
 			case libpf.AbortFrame:
 				// Next step: Figure out how the OTLP protocol

Then run it against local Parca. Parca crashes with this message:

panic: arrow/array: index out of range

goroutine 11552 [running]:
github.com/apache/arrow/go/v16/arrow/array.(*Binary).Value(0x400a24b5c0, 0x0)
        /home/brennan/go/pkg/mod/github.com/apache/arrow/go/[email protected]/arrow/array/binary.go:56 +0x174
github.com/parca-dev/parca/pkg/profile.serializedArrowLocationSize(0x3b30f3, 0x1, 0x0, 0x0, 0x0, {0x400022b577, 0x11, 0x49}, {0x0, 0x0, ...}, ...)
        /home/brennan/code/parca/pkg/profile/encode.go:397 +0x2b8
github.com/parca-dev/parca/pkg/profile.EncodeArrowLocation(0x3b30f3, 0x1, 0x0, 0x0, 0x0, {0x400022b577, 0x11, 0x49}, {0x0, 0x0, ...}, ...)
        /home/brennan/code/parca/pkg/profile/encode.go:296 +0xec
github.com/parca-dev/parca/pkg/normalizer.(*arrowToInternalConverter).AddLocationsRecordV1(0x400a275830, {0x6fd5148, 0x400a23a700}, {0x6ffbe70, 0x400a2963f0})
        /home/brennan/code/parca/pkg/normalizer/arrow.go:587 +0x19fc
github.com/parca-dev/parca/pkg/normalizer.(*arrowToInternalConverter).AddLocationsRecord(0x400a275830, {0x6fd5148, 0x400a23a700}, {0x6ffbe70, 0x400a2963f0})
        /home/brennan/code/parca/pkg/normalizer/arrow.go:130 +0x168
github.com/parca-dev/parca/pkg/profilestore.(*ProfileColumnStore).write(0x4001a1fda0, {0x6fd5148, 0x400a23a700}, {0x6fed460, 0x400a1db790})
        /home/brennan/code/parca/pkg/profilestore/profilecolumnstore.go:270 +0xfe4
github.com/parca-dev/parca/pkg/profilestore.(*ProfileColumnStore).Write.func1()
        /home/brennan/code/parca/pkg/profilestore/profilecolumnstore.go:180 +0x5c
created by github.com/parca-dev/parca/pkg/profilestore.(*ProfileColumnStore).Write in goroutine 11551
        /home/brennan/code/parca/pkg/profilestore/profilecolumnstore.go:179 +0x1e8